Nine out of 10 cells in or on our bodies are microorganisms. The Human Microbiome Project and related research are revealing this complex ecosystem and its relationship to health and disease. Despite the importance of the microbiome, curriculum materials on this topic targeted to secondary students are not yet available. To address this need, the Genetic Science Learning Center (GSLC) at the University of Utah will utilize its award-winning expertise in developing effective multimedia learning experiences to produce a curriculum supplement module on this topic. The materials will engage secondary-level students and teachers as well as the public in exploring the question What is my microbiome and how does it contribute to health and disease? The module will address national science education standards in biology, including cell biology, reproduction, inheritance, matter and energy flow, ecosystems and evolution. These topics are typically taught in separate textbook units or on separate websites. The module thus will link concepts across the curriculum, assisting students in building a deeper understanding of the key biology concepts needed for science literacy, while meeting the need for high-quality, digital curricula designed for 21st Century learners. The goals of the project are to: (1) Educate secondary-level students and teachers about the human microbiome and its contributions to health and disease, and (2) Prepare teachers to use the Your Body's Microbial Ecosystem curriculum module through a national professional development course and workshops at the local, state and national levels. The project will take advantage of the GSLC team's synergistic expertise in science, education, multimedia visualization and evaluation, building on our 16 years of experience in producing highly successful online curriculum materials. The module will be produced using the GSLC's proven curriculum development process, which incorporates a participatory design approach that includes secondary life science teachers, scientists, and our entire team. The module will include (a) inquiry-based, user-focused, multimedia visualizations and interactive learning experiences, (b) user-driven multimedia presentations, (c) Learn More web pages, (d) non-technology-based learning experiences, (e) detailed learning experience guides for teachers, and (f) multimedia teacher professional development materials. The module will be piloted tested in classrooms with diverse students. A small-scale randomized controlled trial will compare the module's efficacy to standard curriculum materials. A professional development summer institute and workshops will prepare approximately 250 teachers from across the US to use the materials with their students. The curriculum module will be freely disseminated worldwide via the GSLC's award-winning Learn.Genetics and Teach.Genetics websites. Based on current usage, the module has the potential to improve biology education for millions of students, over a million teachers and over a million other adults each year.